feat: update deno.json and deno.lock to include OpenAI and Zod imports; add sample PDF file

- Added imports for OpenAI and Zod in deno.json
- Updated deno.lock with new versions for OpenAI and Zod
- Introduced a sample PDF file demonstrating bookmark functionality
- Refactored ai-structured function to improve error handling and logging
- Updated tests to reflect changes in input structure and expected output

deno.json

@@ -1,3 +1,7 @@
 {
-  "allowScripts": ["npm:deno@2.6.4", "npm:supabase-js@1.0.4", "npm:supabase@2.72.6"]
+  "allowScripts": ["npm:deno@2.6.4", "npm:supabase-js@1.0.4", "npm:supabase@2.72.6"],
+  "imports": {
+    "@openai/openai": "jsr:@openai/openai@^6.16.0",
+    "@zod/zod": "jsr:@zod/zod@^4.3.5"
+  }
 }